Removable memory media is becoming an evermore prevalent product for data storage. Removable memory media may include a chip, card, board or device containing a memory or other data store for storing data, which is both installable in a computer or equipment, and removable for upgrade, replacement, security protection (storing in a safe location when not in use), service or reinstallation in a different computer system or equipment. One example of removable memory media is solid state memory. Removability of the removable memory media may be effected by a pluggable connector or by mechanical fasteners, rendering the removable memory media a field replaceable unit (FRU) or simply user removable within an appliance, such as a computer or equipment.
In storage applications, random access memory may be preferable to read only memory because random access memory provides greater data transfer capability. Consequently, in data transactions where consumers require fast access to data, random access memory is the preferred type of memory to serve these types of data transactions. A drawback associated with random access memory is the loss of valid data upon loss of power.
Nonvolatile memory, such as nonvolatile random access memory (NVRAM), is a form of random access memory whose contents remain stored when an appliance is turned off or loses its external power source. The term appliance as used herein may include, for example, a computer or storage controller in which the nonvolatile memory is employed. NVRAM is typically implemented by providing the random access memory with a battery backup. As a result, if the appliance which is employing the NVRAM loses power, the data stored on the NVRAM may be valid and available as long as the battery backup is functional and providing power to the NVRAM.
A problem associated with NVRAM lies in the inability to easily determine whether the data on the NVRAM is available when the appliance employing the NVRAM is powered off. This problem is exacerbated because NVRAM may be implemented on a card or board, and the card may be installed within the chassis of an appliance. Thus, an administrator desiring to know whether the data on the NVRAM is available when the appliance is powered off is typically required to open the chassis, remove the NVRAM card, and test the NVRAM card to determine if the battery has available battery capacity. Further, when transferring NVRAM cards from one appliance to another, which may be necessary during an upgrade of a storage system, it is desirable to know when the data content of the NVRAM is no longer valid due to a failure of its battery. Consequently, a method and system for indicating valid data in a removable memory media is necessary.